1. Technical Field
The present invention relates to a shift lever apparatus, and more specifically to a shift lever apparatus for an automatic transmission of an automotive vehicle, which is provided with both a shift lever lock mechanism and a key interlock mechanism linked with the shift lever lock mechanism.
2. Description of the Related Art
An example of the shift lever apparatus of this type is disclosed in Japanese Published Unexamined (Kokai) Patent Application No. 60-135352, for instance, as shown in FIG. 1. In FIG. 1, a shift lever 1 is pivotally supported by a frame 7 at a base portion la thereof. The shift lever 1 is provided with a position pin 2 movable in the axial direction of the shift lever 1. This position pin 2 is engaged with or disengaged from a position groove 3a formed in a position plate 3 fixed to the frame 7 under such a condition as to be always urged upward. This position pin 2 can be moved downward when a knob button (not shown) attached to a top of the shift lever 1 is pushed.
Further, a bell-crank shaped key lock lever 4 is pivotally supported on the position plate 3. When the position pin 2 is engaged with a Park position P of the position groove 3a, an engage groove 4a of this key lock lever 4 is simultaneously engaged with the position pin 2, as shown in FIG. 1. The key lock lever 4 is a part of a shift lever lock mechanism, and always urged clockwise by an urging means (a spring) (not shown) and further linked with a key interlock mechanism (not shown) via a key lock cable 6. Therefore, the urging means for the key lock lever 4 is also urges the key lock cable 6.
In the prior art shift lever apparatus as described above, however, in the state where an engine key (ignition key) is removed from the key interlock mechanism (i.e., under steering lock condition), when the knob button is pushed to move the position pin 2 downward in order to shift the shift lever 1 from the Park position P to another position, since the key lock lever 4 is locked by the key lock cable 6, whenever the knob button is strongly pushed, the key lock lever 4 locked by the key lock cable 6 is pivoted clockwise, so that there exists such a problem that an excessive force is applied to the key lock cable 6 and thereby the key lock cable 6 is elongated or the key interlock mechanism is unlocked at the worst.
In addition, the width of the engage groove 4a of the key lock lever 4 is determined wider that the diameter of the position pin 2, so that the position pin 2 can be moved smoothly in the vertical direction. However, a play is inevitably produced between the position pin 2 and the engage groove 4a of the key lock lever 4. This play deteriorates the response characteristic of the key lock lever 4, when the position pin 2 located at the Park position P is moved downward. Further, the key interlock function deteriorates because the key lock lever 4 is not pivoted by the key lock cable 6 immediately due to the presence of the play between the position pin 2 and the key lock lever 4.
Furthermore, since the position pin 2 is urged upward and the key lock lever 4 is urged clockwise; that is, the position pin 2 and the key lock lever 4 are urged in the opposite directions with respect to each other, it is necessary to increase the urging force of the position pin 2 than that of the key lock lever 4, so that a larger force is required to push the knob button, thus causing anther problem in that the operability of the shift lever degraded.